feat: add identify protocol example

examples/identify/identify.py

@@ -0,0 +1,132 @@
+import argparse
+import base64
+import logging
+
+import multiaddr
+import trio
+
+from libp2p import (
+    new_host,
+)
+from libp2p.identity.identify.identify import ID as IDENTIFY_PROTOCOL_ID
+from libp2p.identity.identify.pb.identify_pb2 import (
+    Identify,
+)
+from libp2p.peer.peerinfo import (
+    info_from_p2p_addr,
+)
+
+logger = logging.getLogger("libp2p.identity.identify-example")
+
+
+def decode_multiaddrs(raw_addrs):
+    """Convert raw listen addresses into human-readable multiaddresses."""
+    decoded_addrs = []
+    for addr in raw_addrs:
+        try:
+            decoded_addrs.append(str(multiaddr.Multiaddr(addr)))
+        except Exception as e:
+            decoded_addrs.append(f"Invalid Multiaddr ({addr}): {e}")
+    return decoded_addrs
+
+
+def print_identify_response(identify_response):
+    """Pretty-print Identify response."""
+    public_key_b64 = base64.b64encode(identify_response.public_key).decode("utf-8")
+    listen_addrs = decode_multiaddrs(identify_response.listen_addrs)
+    try:
+        observed_addr_decoded = decode_multiaddrs([identify_response.observed_addr])
+    except Exception:
+        observed_addr_decoded = identify_response.observed_addr
+    print(
+        f"Identify response:\n"
+        f"  Public Key (Base64): {public_key_b64}\n"
+        f"  Listen Addresses: {listen_addrs}\n"
+        f"  Protocols: {list(identify_response.protocols)}\n"
+        f"  Observed Address: "
+        f"{observed_addr_decoded if identify_response.observed_addr else 'None'}\n"
+        f"  Protocol Version: {identify_response.protocol_version}\n"
+        f"  Agent Version: {identify_response.agent_version}"
+    )
+
+
+async def run(port: int, destination: str) -> None:
+    localhost_ip = "0.0.0.0"
+
+    if not destination:
+        # Create first host (listener)
+        listen_addr = multiaddr.Multiaddr(f"/ip4/{localhost_ip}/tcp/{port}")
+        host_a = new_host()
+
+        async with host_a.run(listen_addrs=[listen_addr]):
+            print(
+                "First host listening. Run this from another console:\n\n"
+                f"python identify.py -p {int(port) + 1} "
+                f"-d /ip4/{localhost_ip}/tcp/{port}/p2p/{host_a.get_id().pretty()}\n"
+            )
+            print("Waiting for incoming identify request...")
+            await trio.sleep_forever()
+
+    else:
+        # Create second host (dialer)
+        print(f"dialer (host_b) listening on /ip4/{localhost_ip}/tcp/{port}")
+        listen_addr = multiaddr.Multiaddr(f"/ip4/{localhost_ip}/tcp/{port}")
+        host_b = new_host()
+
+        async with host_b.run(listen_addrs=[listen_addr]):
+            # Connect to the first host
+            maddr = multiaddr.Multiaddr(destination)
+            info = info_from_p2p_addr(maddr)
+            print(f"Second host connecting to peer: {info.peer_id}")
+
+            await host_b.connect(info)
+            stream = await host_b.new_stream(info.peer_id, (IDENTIFY_PROTOCOL_ID,))
+
+            try:
+                print("Starting identify protocol...")
+                response = await stream.read()
+                await stream.close()
+                identify_msg = Identify()
+                identify_msg.ParseFromString(response)
+                print_identify_response(identify_msg)
+            except Exception as e:
+                print(f"Identify protocol error: {e}")
+
+            return
+
+
+def main() -> None:
+    description = """
+    This program demonstrates the libp2p identify protocol.
+    First run 'python identify.py -p <PORT>' to start a listener.
+    Then run 'python identify.py -p <ANOTHER_PORT> -d <DESTINATION>'
+    where <DESTINATION> is the multiaddress shown by the listener.
+    """
+
+    example_maddr = (
+        "/ip4/127.0.0.1/tcp/8888/p2p/QmQn4SwGkDZkUEpBRBvTmheQycxAHJUNmVEnjA2v1qe8Q"
+    )
+
+    parser = argparse.ArgumentParser(description=description)
+    parser.add_argument(
+        "-p", "--port", default=8888, type=int, help="source port number"
+    )
+    parser.add_argument(
+        "-d",
+        "--destination",
+        type=str,
+        help=f"destination multiaddr string, e.g. {example_maddr}",
+    )
+    args = parser.parse_args()
+
+    if not args.port:
+        raise RuntimeError("failed to determine local port")
+
+    try:
+        trio.run(run, *(args.port, args.destination))
+    except KeyboardInterrupt:
+        pass
+
+
+if __name__ == "__main__":
+    main()